The present invention relates to a holder for attaching a housing to a rail and a housing comprising at least one such holder.
Particularly in the field of electrical installation, it is frequently necessary to attach various electrical devices to rails, e. g. holding rails with a hat-like cross-sectional configuration. A typical application can be seen in power supplies comprising housings, which need to be secured to a holding rail. In this context, any portions of the housing which are intended to securely attach the housing to the rail need to meet various requirements. Firstly, the housing should be mounted to the rail in a detachable manner. Secondly, the housing must be attached to the rail in a manner preventing any unintentional loosening or detachment of the housing. Finally, in some cases the housing has to be mounted on the rail in such a manner that an electrical contact between these members is ensured so that current can flow to the rail.
DE 196 46 696 C1 discloses a holder and a housing comprising a holder, wherein the holder is made of a section of a metal profile. The holder comprises projections, which are insertable into recesses of the housing""s back wall in such a manner that the holder is secured to the housing. The holder further comprises a recess which is engageable with a projection, preferably an edge of the rail to which the housing is to be mounted. Finally, the holder comprises a comparably small projection, which is associated with the recess, in which the edge of the rail can be accommodated. When the housing is mounted to the rail, the holder is brought into engagement with the edge of the rail by xe2x80x9chookingxe2x80x9d it onto the rail, so that the edge of the rail is located in the recess of the holder. Subsequently, the housing is pivoted somewhat in order to bring the housing towards the rail such that a separate locking member, comprising a biased locking element, can be engaged with the second edge of the rail, which lies opposite to the edge which is accommodated in the recess of the holder. During this pivoting motion, the above-mentioned small projection engages with the rail so that the housing is prevented from sliding or shifting in the longitudinal direction of the rail. However, this effect of the projection can only be guaranteed when the housing is attached to special types of rails having similar cross-sectional configurations. With differing types of rails, this cannot be ensured.
FL 2 694 846 discloses a mounting element for securing electrical devices to rails, wherein the mounting element comprises a flexible element of an approximately circular cross-section, which is used to snap the mounting element to the rail. In other words, the flexible element is somewhat deformed when the mounting element is attached to the rail, and returns to its original shape when the mounting element is in its final attached state. When the mounting element is to be detached, the flexible element again needs to be deformed in order to allow the edge of the rail to pass over the flexible element. However, in the attachment state, the flexible element is in its normal condition so that there is no clamping force applied which would prevent the mounting element from moving in the longitudinal direction of the rail.
Finally, EP 0 703 640 A1 discloses a screwless clamp comprising a flexible element with a first leg and second leg, one of which is moveable, and between which a clamping force is transmitted. The mobility of the flexible element both in the cross-section plane as well as perpendicular thereto is limited, in order to increase the clamping force when the limits of mobility are reached.
The invention was made in order to provide a holder for attaching a housing to a rail as well as a housing provided with such a holder, which is of simple construction and securely prevents a housing from moving in the longitudinal direction of the rail with modifications of standardized rails.
This objective is solved by means of a holder that is securable to a housing and which comprises a recess engageable with a projection of the rail, to which the housing is to be attached, and a flexible member. The flexible member comprises a closed cross-section and is freely deformable in the cross-sectional plane, i.e. in a direction approximately perpendicular to a direction in which the holder is moved towards the rail. In other words, in order to effect attachment, the holder is brought into engagement with or xe2x80x9chooked ontoxe2x80x9d a projection (preferably an edge of the rail) and is pivoted about this point of engagement so that the remainder of the holder is moved towards the rail. During this movement, the flexible member will come into contact with a suitable portion of the rail and will be deformed. Due to the fact that the flexible element is freely deformable in the mentioned direction, the flexible member will deform and thus apply a clamping force acting between the rail and the holder. In particular, the flexible member will remain in its deformed state as long as the housing is attached to the rail so that the clamping force is active in order to prevent the housing from moving or shifting in the longitudinal direction of the rail. Furthermore, free deformability of the flexible member ensures a gradually increasing clamping force without limitations or sudden increases of the clamping force. Finally, the holder according to the invention is configured very simply in that a section of a metal profile can be used and formed with an appropriate recess in order to accommodate the flexible member. Due to the closed cross-section, the flexible member itself is of a simple structure and can be manufactured, handled and mounted to the holder very easily.
Preferably, the flexible member comprises an approximately circular cross-section in order to give the flexible member an especially simple structure.
With regard to the material of the flexible member, plastic material is preferred. In particular, a special type of polyamide has been found to provide the flexible member with the required characteristics and simultaneously permits inexpensive mass production of this member as well as the inventive holder. In order to render the polyamide, which is preferably used for the flexible member, stable in an extended range of temperatures, certain additives are added to the basic polyamide. In this manner, the flexible member of polyamide can be made temperature-stable and flexible at the same time in a temperature range, which extends above 75xc2x0 C.
In order to achieve the above-mentioned objective, the invention further provides a holder for attaching a housing to a rail, the holder being securable to the housing and comprising a recess engageable with a projection of a rail and also a flexible member with a tube-like structure. The tube-shaped flexible member is freely deformable while the holder is moved towards the rail and is brought into contact with the rail. Thus a clamping force is applied by means of the tube-shaped flexible member when a housing is secured to a rail by means of one or more of the described holders. The tube-like structure particularly permits an appropriate combination with a holder made from a section of a metal profile. Furthermore, the tube-shaped flexible member, preferably comprising an approximately circular cross-section, will easily deform from its circular state to an oval state when a gradually increasing clamping force is applied between the holder and the rail. Both with regard to the above described embodiment comprising a flexible member with a tube-like structure, and the embodiment, in which the flexible member comprises an essentially circular cross-section, it should be mentioned that these embodiments are particularly advantageous in that the flexible member with the described structure can be combined with the holder body in a manner to facilitate mounting of the holder to the rail by inserting the projection of the rail into the recess formed in the holder body. Firstly, the recess preferably comprises inclined flanks, in order to promote the inserting motion. Furthermore, this inserting motion is not hindered by the flexible element, which is located nearby the recess, because the flexible element comprises a circular cross-section, in particular a tube-like structure, so that in combination with the inclined flank of the recess axe2x80x94as seen in the cross-sectionxe2x80x94funnel-like structure is formed. Furthermore, the contact point between the flexible member and the holder body can be formed such that any obstacles preventing the mentioned inserting motion are avoided.
In the case of a flexible member comprising a tube-like structure, it is preferred to form a bead or thickened portion around the outer periphery of the flexible member. The bead is capable of engaging a recess formed in the holder body in which the flexible member is accommodated. In other words, the dimension of the bead of the flexible member is adjusted to the size of the recess receiving the flexible member. Due to the fact that the bead can be kept smaller than the full length of the tube-shaped flexible member, a frictional force can be ensured when the flexible member is inserted into its recess, said frictional force being sufficient to retain the flexible member in the recess and simultaneously permit easy assembly of these components.
Also, plastic material (in particular polyamide) is preferred as the material for the flexible member for this embodiment.
As indicated above, in order to achieve the objective underlying the invention, the invention further provides a holder for attaching a housing to a rail, said holder being formed from a portion or section of a metal (preferably an aluminum) profile. In line with the inventive principle, the holder is securable to the housing and comprises a recess which is engageable with a projection of the rail, and a flexible member with a closed cross-section, which is freely deformable in a direction perpendicular to the direction in which the holder is moved towards the rail and brought into contact with the rail. As mentioned above, forming the holder, more specifically the holder body, from a section of a metal profile renders the holder a very inexpensive component. In particular, a metal profile, suitable for attaching the holder to a housing and permitting engagement of the holder with a rail, can be formed by extrusion or by any suitable continuous forming method which produces comparably long profiles of uniform cross-sections. The body of the inventive holder is obtained by means of cutting pieces of such a profile to a length of, for example, 10 mm. In this context, the disclosure of the above-mentioned DE 196 46 696 C1 is incorporated herein by means of this reference, and is considered to be a part of this specification.
In order to achieve the above-mentioned objective, the invention further provides a housing, in particular a power supply housing, which comprises at least one holder in one of the above-mentioned embodiments. Thus, the invention provides a housing comprising at least one holder for attaching the housing to a rail, the holder comprising a recess that is engageable with a projection of the rail, and a flexible member. The flexible member has a closed cross-section and is freely deformable in a direction approximately perpendicular to that direction in which the holder is moved towards the rail, so that the flexible element is deformed as long as the housing is attached to the rail by means of the holder, and a clamping force is applied which prevents the housing from moving in the longitudinal direction of the rail.
The invention further discloses a housing comprising at least one holder for attaching the housing to a rail, the holder comprising a recess which is engageable with a projection of the rail and a flexible member with a tube-like structure. The tube-shaped flexible element, preferably with an approximately circular cross-section will deform to an oval state when the holder is moved towards the rail and brought into contact with the rail. This deformation of the tube-shaped flexible element will apply a firm clamping force during attachment of the housing, so that any movement or shifting of the housing can be securely prevented.
The invention finally provides a housing comprising at least one holder for attaching the housing to a rail, the holder being made of a section of a metal profile. Furthermore, the holder comprises a recess which is engageable with a projection of the rail, and a flexible member with a closed cross-section which is freely deformable in a direction perpendicular to a direction in which the holder is moved towards the rail in order to bring the holder into contact with the rail and thus attach the housing to the rail.
With regard to the housing according to the invention, it is preferred that the housing additionally comprises a locking member for securing the housing to the rail. In other words, the holder is active for hooking the housing onto the rail at one edge of the rail, and the locking member, which is preferably biased into the locking direction, serves to lock the housing to the rail by means of a firm engagement with the opposite edge of the rail.